Dryer appliance with thermal condition detection

ABSTRACT

A dryer appliance operable to detect an extreme thermal event therein and related methods of detecting an extreme thermal event are provided. The dryer appliance includes a cabinet, a drum rotatably mounted within the cabinet, a heating system upstream of the drum, and an outlet duct downstream of the drum. The method includes and/or the dryer is configured for monitoring an outlet temperature, determining a temperature gradient of the monitored outlet temperature, and detecting the extreme thermal event based on the determined temperature gradient.

FIELD OF THE INVENTION

The present subject matter relates generally to dryer appliances, and more particularly to dryer appliances which are configured for detecting thermal conditions therein and related methods.

BACKGROUND OF THE INVENTION

A conventional appliance for drying articles such as a clothes dryer (or laundry dryer) for drying clothing articles typically includes a cabinet having a rotating drum for tumbling clothes and laundry articles therein. One or more heating elements heat air prior to the air entering the drum, and the warm air is circulated through the drum as the clothes are tumbled to remove moisture from laundry articles in the drum. Gas or electric heating elements may be used to heat the air that is circulated through the drum.

In some circumstances, the thermal conditions in the dryer appliance may unintentionally exceed the normal operating parameters. For example, the level of heat, or temperature, within the drum may be too high. In such circumstances, it is desirable to detect the excessive thermal condition as quickly as possible after the conditions arise in order to promptly mitigate the excessive thermal conditions.

Accordingly, a dryer appliance having features for improved detection of excessive thermal conditions and related methods would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In an exemplary aspect of the present disclosure, a method of detecting an extreme thermal event in a dryer appliance is provided. The dryer appliance includes a cabinet, a drum rotatably mounted within the cabinet, a heating system upstream of the drum, and an outlet duct downstream of the drum. The method includes monitoring a temperature at the outlet duct of the dryer appliance and determining a temperature gradient of the monitored temperature at the outlet duct of the dryer appliance. The method also includes detecting the extreme thermal event based on the determined temperature gradient. After detecting the extreme thermal event, the method includes completely shutting down the dryer appliance.

In another exemplary aspect of the present disclosure, a dryer appliance operable to detect an extreme thermal event therein is provided. The dryer appliance includes a cabinet with a drum rotatably mounted within the cabinet. The drum defines a chamber for the receipt of articles for drying. The dryer appliance also includes a heating system. The heating system is fluidly coupled to the drum such that heated air flows from the heating system to the chamber of the drum for drying of articles therein. An outlet duct is fluidly coupled to the drum downstream of the chamber. The dryer appliance further includes a controller. The controller is configured to monitor a temperature at the outlet duct and determine a temperature gradient of the monitored temperature at the outlet duct. The controller is also configured to detect the extreme thermal event based on the determined temperature gradient. After detecting the extreme thermal event, the controller is configured to completely shut down the dryer appliance.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides a perspective view of a dryer appliance in accordance with exemplary embodiments of the present disclosure.

FIG. 2 provides a perspective view of the example dryer appliance of FIG. 1 with portions of a cabinet of the dryer appliance removed to reveal certain components of the dryer appliance.

FIG. 3 provides a graph of outlet temperature over time during a plurality of exemplary dryer appliance operations.

FIG. 4 provides a graph of the rate of change in the outlet temperature over time during a plurality of exemplary dryer appliance operations.

FIG. 5 provides a graph of the moving summation of the outlet temperature over time during a plurality of exemplary dryer appliance operations.

FIG. 6 provides a graph of the total time the outlet temperature exceeds a temperature threshold over time during a plurality of exemplary dryer appliance operations.

FIG. 7 provides a flow chart of an exemplary method of operating a dryer appliance according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, terms of approximation, such as “generally,” or “about” include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, “generally vertical” includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

Turning now to the figures, FIG. 1 provides dryer appliance 10 according to exemplary embodiments of the present disclosure. FIG. 2 provides another perspective view of dryer appliance 10 with a portion of a cabinet or housing 12 of dryer appliance 10 removed in order to show certain components of dryer appliance 10. Dryer appliance 10 generally defines a vertical direction V, a lateral direction L, and a transverse direction T, each of which is mutually perpendicular, such that an orthogonal coordinate system is defined. While described in the context of a specific embodiment of dryer appliance 10, using the teachings disclosed herein, it will be understood that dryer appliance 10 is provided by way of example only. Other dryer appliances having different appearances and different features may also be utilized with the present subject matter as well.

Cabinet 12 includes a front panel 14, a rear panel 16, a pair of side panels 18 and 20 spaced apart from each other by front and rear panels 14 and 16, a bottom panel 22, and a top cover 24. Within cabinet 12, an interior volume 29 is defined. A drum or container 26 is mounted for rotation about a substantially horizontal axis within the interior volume 29. Drum 26 defines a chamber 25 for receipt of articles of clothing for tumbling and/or drying. Drum 26 extends between a front portion 37 and a back portion 38. Drum 26 also includes a back or rear wall 34, e.g., at back portion 38 of drum 26. A supply duct 41 may be mounted to rear wall 34 and receives heated air that has been heated by a heating assembly or system 40.

As used herein, the terms “clothing” or “articles” includes but need not be limited to fabrics, textiles, garments, linens, papers, or other items from which the extraction of moisture is desirable. Furthermore, the term “load” or “laundry load” refers to the combination of clothing that may be washed together in a washing machine or dried together in a dryer appliance 10 (e.g., clothes dryer) and may include a mixture of different or similar articles of clothing of different or similar types and kinds of fabrics, textiles, garments and linens within a particular laundering process.

A motor 31 is provided in some embodiments to rotate drum 26 about the horizontal axis, e.g., via a pulley and a belt (not pictured). Drum 26 is generally cylindrical in shape, having an outer cylindrical wall 28 and a front flange or wall 30 that defines an opening 32 of drum 26, e.g., at front portion 37 of drum 26, for loading and unloading of articles into and out of chamber 25 of drum 26. A plurality of lifters or baffles 27 are provided within chamber 25 of drum 26 to lift articles therein and then allow such articles to tumble back to a bottom of drum 26 as drum 26 rotates. Baffles 27 may be mounted to drum 26 such that baffles 27 rotate with drum 26 during operation of dryer appliance 10.

Drum 26 includes a rear wall 34 rotatably supported within main housing 12 by a suitable fixed bearing. Rear wall 34 can be fixed or can be rotatable. Rear wall 34 may include, for instance, a plurality of holes that receive hot air that has been heated by a heating system 40, as will be described further below. Moisture laden, heated air is drawn from drum 26 by an air handler, such as blower fan 48, which generates a negative air pressure within drum 26. The air passes through a duct 44 enclosing screen filter 46, which traps lint particles. As the air passes from blower fan 48, it enters a duct 50. In some embodiments, the air in the duct 50 then is passed into heating system 40, e.g., as illustrated in FIG. 2. In other embodiments, the air from the duct 50 may be vented or exhausted outside of the dryer appliance and the heating system 40 may be coupled to a direct inlet which draws in air from outside the dryer appliance 10 into the heating system 40, e.g., directly into the heating system 40, such as without passing through any other components of the dryer appliance 10 before the heating system 40 (apart from the inlet itself).

In various embodiments, the heating system 40 may be or include an electric heater, a gas-burning heater, and/or other suitable heating element. Heated air exits heating system 40 and flows to drum 26 by duct 41. After the clothing articles have been dried, they are removed from the drum 26 via opening 32. A door 33 provides for closing or accessing drum 26 through opening 32.

In some embodiments, one or more selector inputs 70, such as knobs, buttons, touchscreen interfaces, etc., may be provided or mounted on a cabinet 12 (e.g., on a backsplash 71) and are in operable communication (e.g., electrically coupled or coupled through a wireless network band) with a processing device or controller 90. A display 56 may also be provided on the backsplash 71 and may also be in operable communication with the controller 90. Controller 90 may also be provided in operable communication with motor 31, blower 48, or heating system 40. In turn, signals generated in controller 90 direct operation of motor 31, blower 48, or heating system 40 in response to the position of inputs 70. As used herein, “processing device” or “controller” may refer to one or more microprocessors, microcontroller, ASICS, or semiconductor devices and is not restricted necessarily to a single element. The controller 90 may be programmed to operate dryer appliance 10 by executing instructions stored in memory (e.g., non-transitory media). The controller 90 may include, or be associated with, one or more memory elements such as RAM, ROM, or electrically erasable, programmable read only memory (EEPROM). For example, the instructions may be software or any set of instructions that when executed by the processing device, cause the processing device to perform operations. It should be noted that controllers as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein. For example, in some embodiments, methods disclosed herein may be embodied in programming instructions stored in the memory and executed by the controller.

Additionally, a temperature sensor 51 (FIG. 2) such as a thermistor or any other suitable temperature sensor may be provided to sense a temperature downstream of the drum 26 and/or the chamber 25 therein, e.g., downstream with respect to the flow of heated air from the heating system 40. For example, as illustrated in FIG. 2, the temperature sensor 51 may be configured to sense a temperature of air flowing from the chamber 25 in the duct 50. In various embodiments, one or more temperature sensors may be provided. The temperature sensor(s) may be in operable communication (e.g., electrically coupled or coupled through a wireless network band) with the controller 90.

Turning now to FIG. 3, a graph of outlet temperature in a dryer appliance over time during a plurality of dryer operations is provided. The outlet temperature may be measured with, e.g., the temperature sensor 51 (FIG. 2) in the outlet duct 50. In particular, six dryer operations are graphed in FIG. 3. During three of the operations, represented by dashed lines 100, 102, and 104, the outlet temperature remained within a normal or expected range throughout the operation. In the other three operations, represented by solid lines 200, 202, and 204, the outlet temperature exceeded the normal or expected range. Thus, lines 200, 202, and 204 represent dryer operations wherein an extreme or excessive thermal condition or event occurred. As may be seen in FIG. 3, if a threshold or setpoint were used to detect the extreme thermal event, such detection may be undesirably delayed. For example, the threshold or setpoint may be as high as 165° F., which in some cases may take as long as about a minute or more to detect the extreme thermal event. In contrast, embodiments of the present disclosure may permit detection of an extreme thermal event much sooner, such as in about fifteen seconds or less, such as in about ten seconds or less, such as in about five seconds.

As may be seen in FIG. 3, e.g., by comparing the slopes and peak values of lines 100, 102, and 104 with those of lines 200, 202, and 204, during an extreme thermal event, the outlet temperature rises significantly and at a much faster rate than during normal operation. Thus, as will be explained in more detail below, embodiments of the present disclosure include dryer appliances configured for and methods that include detecting an extreme thermal event based on the rate of change in the outlet temperature, e.g., a temperature gradient of the outlet temperature. In various embodiments, such detection may be based on a current value of the gradient exceeding a threshold, the moving summation of the gradient exceeding a threshold, or the length of time (consecutively or non-consecutively) that the gradient has exceeded a threshold exceeding a time limit or cumulative time threshold.

For example, as illustrated in FIG. 4, the outlet temperature gradient or slope during a normal operation is represented by dashed line 400, whereas the outlet temperature gradient during an extreme thermal event is represented by the solid line 402. As may be seen in FIG. 4, using the temperature gradient to detect an extreme thermal event allows rapid detection of the extreme thermal event, such as in less than about ten seconds if the gradient threshold is about three or about four. The temperature gradient may be determined by calculating a straight-line slope between two chronologically separated outlet temperature values, e.g., a first outlet temperature measured at a first time and a second outlet temperature measured at a second time which is subsequent to the first time. The gradient may, in at least some embodiments, be the mathematical difference between the second temperature and the first temperature, e.g., the second temperature minus the first temperature, such as the current temperature minus the temperature N seconds ago. For example, the second time may occur N seconds after the first time. In some embodiments, N may be a whole number (integer). In various embodiments, N may be between about two seconds and about ten seconds, such as between about three seconds and about eight seconds, such as about five seconds. In such embodiments, the gradient threshold value may be proportional to the value of N, e.g., when a larger value of N is used, a larger gradient threshold (in comparison to a gradient threshold value which may be used with a lower value of N) may also be used. For example, with an N value of 5, the gradient threshold may be about 4.

FIG. 5 provides a graph of a moving summation of the outlet temperature gradient over time during two different dryer operations. During a first dryer operation, as represented by dashed line 500 in FIG. 5, the moving summation remains relatively constant and remains about zero. During a second dryer operation, as represented by solid line 502 in FIG. 5, the moving summation increases rapidly during the initial about ten seconds of the dryer operation and varies over a wider range (as compared to the range during the first operation represented by line 500). Thus, in some embodiments, the extreme thermal event may be detected based on the temperature gradient by tracking a moving summation of the temperature gradient and detecting the extreme thermal event when the moving summation exceeds a summation threshold. As can be seen in the examples illustrated in FIG. 5, the extreme thermal event may be detected in as little as about five seconds or less using the moving summation of the temperature gradient, e.g., when the summation threshold for detecting the extreme thermal event is about ten or about fifteen. Additionally, using the moving summation of the temperature gradient may reduce or eliminate false positives due to a spike in temperature or an outlier temperature reading.

FIG. 6 provides a graph of the cumulative time (consecutive or non-consecutive) that the temperature gradient is above a gradient threshold for both a normal dryer operation, represented by dashed line 600, and an extreme thermal event, represented by solid line 602. In some embodiments, detecting an extreme thermal event based on the temperature gradient may include detecting the extreme thermal event when the cumulative time that the temperature gradient is above a gradient threshold is greater than a cumulative time threshold. Similar to the moving summation, the cumulative time threshold minimizes or avoids false positives from a temperature spike or other outlier temperature value. As may be seen by comparing the dashed line 600 with the solid line 602 in FIG. 6, the extreme thermal event (602) may be readily distinguished from the normal dryer operation (600). For example, using a cumulative time threshold of about five seconds would permit detection of the extreme thermal event represented by solid line 602 in about fifteen seconds or less, such as in about ten seconds or less.

FIG. 7 provides a flowchart of an exemplary method 700 of detecting an extreme thermal event in a dryer appliance, which in some embodiments may be the dryer appliance 10 described above. As illustrated in FIG. 7, the method 700 may include a step 702 of monitoring a temperature at the outlet duct of the dryer appliance. For example, the outlet temperature may be monitored, e.g., repeatedly or continuously measured, using an outlet thermistor such as the outlet thermistor 51 described above.

The method 700 may also include a step 704 of determining a temperature gradient of the monitored temperature at the outlet duct of the dryer appliance. In some embodiments, determining the temperature gradient may include calculating the difference between a current temperature at the outlet duct of the dryer appliance and a previous temperature at the outlet duct of the dryer appliance, such as by subtracting the previous temperature from the current temperature. The previous temperature at the outlet duct of the dryer appliance may be chronologically separated from the current temperature by a predetermined time period. For example, the predetermined time period may be N seconds, and in some embodiments, N is a whole number. In various embodiments, the predetermined time period may be between about three seconds and about ten seconds, such as about seven seconds or about five seconds.

In some embodiments, e.g., as illustrated in FIG. 7, the method 700 may further include a step 706 of detecting the extreme thermal event based on the determined temperature gradient. In various embodiments, detecting the extreme thermal event based on the determined temperature gradient may include comparing the thermal gradient to a gradient threshold. In some embodiments, the extreme thermal event may be detected when the thermal gradient, e.g., a current value of the thermal gradient, exceeds the gradient threshold. In additional embodiments, the total cumulative time that the temperature gradient exceeds the gradient threshold, consecutively or intermittently, may be calculated and compared to a cumulative time threshold. In such embodiments, the extreme thermal event may be detected based on the temperature gradient when the cumulative time that the temperature gradient exceeds the gradient threshold is greater than the cumulative time threshold. In additional exemplary embodiments, detecting the extreme thermal event based on the determined temperature gradient may include calculating a moving summation of the temperature gradient, comparing the moving summation of the temperature gradient to a summation threshold, and detecting the extreme thermal event based on the determined temperature gradient when the moving summation of the temperature gradient exceeds the summation threshold.

Also as illustrated in FIG. 7, in some embodiments, the method 700 may further include completely shutting down the dryer appliance after detecting the extreme thermal event, e.g., because of the detected thermal event. Completely shutting down the dryer appliance includes deactivating the air handler and/or fan as well as deactivating the heating system.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A method of detecting an extreme thermal event in a dryer appliance, the dryer appliance comprising a cabinet, a drum rotatably mounted within the cabinet, a heating system upstream of the drum, and an outlet duct downstream of the drum, the method comprising: monitoring a temperature at the outlet duct of the dryer appliance; determining a temperature gradient of the monitored temperature at the outlet duct of the dryer appliance; detecting the extreme thermal event based on the determined temperature gradient; and completely shutting down the dryer appliance after detecting the extreme thermal event.
 2. The method of claim 1, wherein determining the temperature gradient comprises calculating the difference between a current temperature at the outlet duct of the dryer appliance and a previous temperature at the outlet duct of the dryer appliance.
 3. The method of claim 2, wherein the previous temperature at the outlet duct of the dryer appliance is chronologically separated from the current temperature by a predetermined time period.
 4. The method of claim 3, wherein the predetermined time period is N seconds, and wherein N is a whole number.
 5. The method of claim 3, wherein the predetermined time period is between about three seconds and about ten seconds.
 6. The method of claim 1, wherein detecting the extreme thermal event based on the determined temperature gradient comprises comparing a current value of the temperature gradient to a threshold and detecting the extreme thermal event based on the current value of the determined temperature gradient exceeding the threshold.
 7. The method of claim 1, wherein detecting the extreme thermal event based on the determined temperature gradient comprises comparing a moving summation of the temperature gradient to a threshold and detecting the extreme thermal event based on the moving summation of the determined temperature gradient exceeding the threshold.
 8. The method of claim 1, wherein detecting the extreme thermal event based on the determined temperature gradient comprises determining a total cumulative length of time the temperature gradient has exceeded a threshold and detecting the extreme thermal event based on the total cumulative length of time the temperature gradient has exceeded the threshold being greater than a cumulative time threshold.
 9. The method of claim 1, wherein monitoring the temperature at the outlet duct of the dryer appliance comprises continuously measuring an air temperature in the outlet duct of the dryer appliance with a thermistor in the outlet duct.
 10. A dryer appliance operable to detect an extreme thermal event therein, the dryer appliance comprising: a cabinet; a drum rotatably mounted within the cabinet, the drum defining a chamber for the receipt of articles for drying; a heating system fluidly coupled to the drum whereby heated air flows from the heating system to the chamber of the drum for drying of articles therein; an outlet duct fluidly coupled to the drum downstream of the chamber; and a controller, the controller configured to: monitor a temperature at the outlet duct; determine a temperature gradient of the monitored temperature at the outlet duct; detect the extreme thermal event based on the determined temperature gradient; and completely shut down the dryer appliance after detecting the extreme thermal event.
 11. The dryer appliance of claim 10, wherein the controller is configured to determine the temperature gradient by calculating the difference between a current temperature at the outlet duct of the dryer appliance and a previous temperature at the outlet duct of the dryer appliance.
 12. The dryer appliance of claim 11, wherein the previous temperature at the outlet duct of the dryer appliance is chronologically separated from the current temperature by a predetermined time period, the predetermined time period stored in a memory of the controller.
 13. The dryer appliance of claim 12, wherein the predetermined time period stored in the memory of the controller is N seconds, and wherein N is a whole number.
 14. The dryer appliance of claim 12, wherein the predetermined time period stored in the memory of the controller is between about three seconds and about ten seconds.
 15. The dryer appliance of claim 10, wherein the controller is configured to detect the extreme thermal event based on the determined temperature gradient by comparing a current value of the temperature gradient to a threshold and detecting the extreme thermal event based on the current value of the determined temperature gradient exceeding the threshold.
 16. The dryer appliance of claim 10, wherein the controller is configured to detect the extreme thermal event based on the determined temperature gradient by comparing a moving summation of the temperature gradient to a threshold and detecting the extreme thermal event based on the moving summation of the determined temperature gradient exceeding the threshold.
 17. The dryer appliance of claim 10, wherein the controller is configured to detect the extreme thermal event based on the determined temperature gradient by determining a length of time the temperature gradient has exceeded a threshold and detecting the extreme thermal event based on the length of time the temperature gradient has exceeded the threshold being greater than a time limit.
 18. The dryer appliance of claim 10, wherein the controller is configured to monitor the temperature at the outlet duct of the dryer appliance by continuously measuring an air temperature in the outlet duct of the dryer appliance with a thermistor in the outlet duct. 